Bore hole pump



May 18, 1943.

BORE HOLE PUMP Filed July 22, 1941 l. s. SALNIKOV 3 Sheets-Sh 1 g 4 F/G.L

9 [M INVEIIVTOR,

ATTORNEY May 18, 1943. s. SALNIKOV BORE HOLE PUMP Filed July 22/1941 .3Sheets-Sheet 2 INVENTOR. BY

ATTORNEY May 18, 1943., s. SALNIKOV 2,319,749

BORE HOLE PUMP Filed July 22. 1941 3 Sheets-Sheet 3 Patented May 18,1943 BORE HOLE PUMP Ivan S. Salnlkov, Tulsa, Okla., assignor to Standan! Oil Development Company, a corporation of Delaware Application July22, 1941, Serial No. 403,501

Claims.

The present invention relates to bore hole pumps.

In the past, oil or other fluid occurring in a sub-stratum has beenbrought to the surface either by being allowed to flow to the surfaceunder its own pressure or, where sufficient formation pressure did notexist, by pumping or gas lifting. Bore hole pumps, particularly for deepwells, in general, suffer from the disadvantage that the eiliciency ofthe pump decreases with depth. The principal reason for this loss ofefficiency is that as depth increases, in order .to stay within thelimits of tensile strength of the sucker rods it is necessary to reducethe diameter of the piston which in turn reduces the capacity of thepump,

According to the present invention advantage is taken of the fact thatin deep wells, long strings of tubing must be employed and under theinfluence of pressure this tubing can be made to elongate to the extentthat its lower end may travel a distance of many feet depending'upon theoverall length of the tubing. Therefore, by the present invention, thesucker rod is eliminated and is replaced by the tubing itself which,however, is not reciprocated in the manner of conventional sucker rods,but is subjected to fluctuations in pressure which cause its lower endto reciprocate in the manner of a piston.

In the system of the present invention the lower end of the tubing isformed with an enlarged head which acts as a piston and which moves in acylinder provided for the purpose, said cylinder being mountedindependently of the tubing. Hydraulic pressure is then applied to theupper face of the enlarged head of the tubing causing the tubing toelongate and the enlarged head to move downwardly in the piston. Thisbuilds up pressure under the lower end of said enlarged head and thispressure is utilized to pump oil to the surface. When the pressure onthe upper side of said enlarged head is released, the tubing contractscausing the enlarged head to move upwardly thereby creating suctionbeneath the lower face of the enlarged head and sucking oil out of theformation.

The principal object of the present invention, therefore, is theprovision of a pumping system and apparatus in which advantage is takenof the considerable amount of elongation which long strings of tubingwill undergo with increases in pressure. An additional object of thepresent invention is the provision of a pump of the character describedin which the tubing itself is caused to act, in effect, as a piston byhaving its lower end reciprocated in response to intermittent increasesand drops in pressure applied at the surface.

An additional object of the present invention is provision of a borehole pump which will be simple in construction and possessed of aminimum number of moving parts and which will be entirely free fromfrictional elements which require lubrication. Among the advantages ofthe pump in the present invention are that its operation is subject tofull control from the surface and that due to its construction there isvery little chance for it to get out of order whereby the frequency withwhich it must be withdrawn from the bore hole is dictated solely by thedurability of the metals which make up the moving parts.

Further objects and advantages of the present invention will appear fromthe following detailed description of the accompanying drawings, inwhich Fig. 1 is a front elevation partly in section of one embodiment ofthe pumping system of the present invention;

Fig. 2 is a similar view of a modified form of the embodiment shown inFig. 1; and,

Fig. 3 is a similar view of still another embodiment of the presentinvention.

Referring to the drawings in detail and particularly to Fig. 1, numeralI designates a bore hole drilled from the surface to a producing hori--zon 2. The bore hole is lined with casing 3 which is sealed off at thesurface by casing head 4 which may be provided with a gas draw-off line5. Mounted on the casing head is a tubing head 6 which carries a tubing1 suspended in the bore hole and of suflicient depth so that its lowerend will be in the vicinity of the producing formation. Connected to thetubing head 6 is a drawoff line 8 which is adapted tov carry away anyfluid which is brought up through the tubing 1.

Threaded to the lower end of the tubing 1 is a cylinder 9 which has alength, which will vary with the depth of the well and operatingconditions to be employed, which will determine the amount of travel ofa piston in this cylinder. In other words, the cylinder is made longenough to provide a full travel for the piston, to be hereinafterdescribed. The lower end of the cylinder rests on a packing disc II)which is carried by acylindrical block I! which in turn is threaded intoa collar H. The upper end of the collar I! has screw thread engagementwith an outer cylinder I3 which is of larger diameter than cylinder 9and concentric therewith so that an annular space I4 is formed betweenthem. The upper end of cylinder I3 is threaded into a skirt H which iswelded to the upper end of cylinder 9. The block H is placed against thelower end of cylinder 9 by screwing the collar i2 onto the lower end ofcylinder i3. Screwed intothe lower end of collar I2 is a barrel i6having an opening il! in its bottom over which is mounted a cagecarrying a check valve i8.

Block H has a longitudinal passage l9 connecting the interior ofcylinder 9 with the interior of barrel l5. Block II also has a transverse passage 20 which terminates at its either end at the upper face ofthe block in fluid communication with the cylinder i3. This transversepassage is connected to the interior of the barrel l8 by a longitudinalpassage 2| in which is mounted a check valve 22.

Mounted on top of tubing head 6 is another tubing head 23 from which issuspended a tubing 24 which-is substantially co-extensive with tub-'ing 1. At its lower end tubing 24 is formed into a plunger 25 which hasafluid-tight fit with the inner surface of cylinder 9 and is providedwith suitable packing rings 26. Just above the plunger 25 the tubing isprovided with an opening 21. In the upper end of cylinder 9 is rigidlyfixed a. sleeve 28 which has a diameter considerably smaller than thatof cylinder 9 and which forms a cylinder for a piston 29 formed ontubing 24. Like the plunger 25 piston 29 is provided with suitablepacking 30. The upper end of tubing 24 is connected to a line 3| whichdischarges into a tank 32. A branch line 33 is connected to line 3| andat their junction is a special valve 34 which can be manipulated toconnect line 3| to tank 32 or to the branch line 33 as desired and whichis preferably an automatic valve for making connections alternately atsome selected frequency. Branch line 33 is the discharge line of pump35. The intake line 36 is connected to the lower end of tank 32. Aby-pass 31 is provided between lines 33 and 36 so that when valve 34 isclosed against discharge line 33 the pump can continue to operate. Inother words, the pump operates continuously and is only intermittentlyconnected to line 3|.

As previously indicated the dimensions of the various parts of the pumpare selected to suit a particular operating depth. For example, whenproducing from a formation of about 7500 feet, the cylinder 9 may befrom 4 to 10 feet between the lower end of sleeve 28 and block dependingupon the pressure which is to be applied by the pump. Of course, thelength of the sleeve 28 will be about the same. because the piston 29must have the same length of travel as the plunger 25. It will beunderstood, of course, that the dimensions of these parts will vary withdifferent pumping depths and metals, as the tensile strength andresilience of these materials vary with depth and with the amount ofpressure to be applied.

In operation, with the pump 35 disconnected from line 3|, the plunger 25will occupy a position adjacent to the lower end of sleeve 28. At thispoint the check valves l8 and 22 will be seated and cylinder 9 andbarrel l6 will be full of oil, as will also the annular space l4 andtubing 1 up to a certain level. It will be noted at this point thatthere are fluid connections 38 between annular space l4 and tubing 1above piston 29. The pump is then connected to line 3| and high pressurefluid is forced into tubing 24, and discharges through opening 21against the upper side of the plunger 25. As the pressure builds up thetubing 24 will elongate causing the plunger 25 to travel downwardly. Itwill be noted that this downward thrust of pressure would normally tendto cause tubing I to elongate, but this elongation of tubing 1 isopposed by the upward thrust of pressure against the lower annular faceof the sleeve 28 which in effect forms a piston acting in opposition tothe tendency of tubing i to elongate.

As plunger 25 moves downwardly it builds up pressure in the barrel i6forcing ball I8 on its seat and ball 22 off its seat whereby the oil inthe cylinderv 9 and barrel I6 is caused to flow through lenticularpassage 20 into annular space l4 and thus into tubing 1 and draw-oilline 8.

When the plunger 25 reaches the bottom of its stroke the valve 34 ismanipulated to disconnect line 3! from pump 35 and connect it to tank32. This releases the pressure on the upper face of plunger 25 andpermits the tubing 24 to contract drawing'the plunger upwardly incylinder 9. At thi point the ball 22 is forced on its seat by the headof'liquid above it and as plunger 25 moves upwardly it creates a suctionwhich decreases the pressure in barrel I6 to the point where theformation pressure can force the ball I8 off its seat permitting oil toflow in from the formation to flll barrel l6 and cylinder 9. After theplunger 25 has reached its upper extreme position the parts are then inposition to start another cycle.

In order to compensate for the different weight on the different lengthsof tubing in string, and thereby to more evenly distribute theelongation of the tubing,'it is advantageous to make the tubing 24 ofdifferent thickness at different depths, the thickness being greatest atthe surface and diminishing with depth. By this expedient localizedpoints of excessive fatigue may be avoided.

In Fig. 2, parts corresponding to parts shown in Fig. 1 carry the samenumerals. The embodiment shown in Fig. 2 is identical with that shown inFig. l with the exception that provision I is made to eliminate thepossibility of gas lock occurring beneath the plunger in cylinder 3. Forthis purpose. tubing 24 carries an inner length of tubing of smallerdiameter indicated by numeral 39. This inner length of tubing connectsto the interior of tubing 1 through a T connection 40 located above thepiston 29. The relative diameters of tubing 24 and 33 are such that anannular space is formed between them to provide for the passage of fluidthrough tubing 24 to outlet 21. The lower end of tubing 39 is threadedinto the plunger 25 which for this purpose is provided with a centralpassage 4| in which is' seated a check valve 42. With this arrangementwhen the plunger 25 moves downwardly, fluid flows upwardly in not onlythrough check valve 22 but through check valve 42 with the result thatany gas which may have collected above the surface of liquid in thecylinder 3 will be carried out of the cylinder through tubing 39 anddischarged into tubing 1.

In the embodiment shown in Fig. 3, it will be noted that a simplifiedform of surface equipment is illustrated. It will be understood thateither this or the equipment shown in Figs. 1 and 2 may be employed inany case or any other equipment may be employed which will function tosupply hydraulic pressure to the plunger in the bore holeintermittently. In the surface equipment in Fig. 3, line 3| is connectedto a cylinder 43 which is provided with a piston 44 actuated by suitableengine 45. The piston has a longitudinal passage 46 provided with asafety valve 41 which may be set to maintain any desired maximumpressure in the working system. A reservoir 48 is shown connected to thecylinder 43 by pipe 49 which is so located that it,

forms a fluid connection between reservoir 48 and cylinder 43 on eitherside of the piston 44, depending on the position of the latter.Reservoir 43 is also connected to the rear end of the cylinder by a pipe50. In the embodiment shown in Fig. 3 casing 3, tubing 1, and tubing 24are the same as in Figs. 1 and 2. The difference between this embodimentand the others, in addition to the surface equipment, lies in thecombination of elements connected to the lower end of the tubings I and24.

The lower end of tubing I is connected by an adapter 3| to a cylinder ofsmaller diameter 52 which is equivalent to the cylinder formed by sleeve28 in Figs. 1 and 2. The lower end of this cylinder is in turn connectedby an adapter 53 to a larger diameter cylinder 54 corresponding tocylinder 3 in Figs. 1 and 2. The lower end of cylinder 54 carries acollar 55 which in turn carries a check valve assembly 56 having acentral passage 51 and a ball valve 58.

Threaded on to the lower end of tubing-24 is a fitting 53 which carriesat its lower end, a length of tubing 80. As shown, this tubing isprovided with special rings 6| which are of an outside diameter suchthat they form a snug fluid tight flt with the interior surface ofcylinder 52. The space between these rings will ordinarily carry oilwhich will act as a lubricant and seal. This ringed tubing is commonlyknown in the art as a grooved plunger. The tubing 60 extends down intothe cylinder 54 and terminates in a head 62 which has a fluid tight fitwith the interior surface of cylinder 54. The lower end of plunger 62has a reduced diameter on which are arranged sealing cups 63 held inplace by cap 64 which has a central opening 66 on which is seated a ball66. The tube 60 is provided with perforations 81 just above the plunger62.

The plunger 62 has a central opening in which is secured the lower endof an inner tubing 68,

the upper end of which terminates in the fitting full of power fluid.Likewise, the cylinder 43 on both sides of the piston is always full ofthis fluid.

At the beginning of a cycle the piston 44 is at the rear end of cylinder43 and reservoir 48 is in open communication with the rest of the powerfluid system. After the piston moves forward it seals off the reservoirfrom the rest of the system and builds up pressure in the rest of thesystem which results in a force exerted on the upperside of the plungeron head 62.- As this force increases the tubing 24 elongates and theplunger moves downward in cylinder 54. It may be noted here that thespace between the large and small diameters of adapter 53 forms aworking surface against which the pressure in cylinder 54 is thrust tooffset the tendency of tubing 1 to elongate. In fact, the thrust againstthis working surface is suiliciently great to compensate for a portionof the weight oi the tubing I whereby this tubing actually contracts andthereby adds to the effective working stroke of the plunger.

As the plunger moves downwardly ball 58 is thrust on its seat and ball86 is moved off its seat permitting the oil collected in the cylinder 54to move upwardly through tubing 68 and into tubing 1 and thence to thesurface. When the stroke of the plunger is completed the piston 44 isdrawn back into cylinder 43, releasing pressure on top of the plungerand permitting tubing 24 to contract. At the same time tubing 1elongates an amount equal to that which it contracted during the backstroke. It will be noted from the above discussion that the particularembodiments shown are illustrative only and are not presented as beingdefinitive of the scope of the present invention. The basic feature ofthe present invention is the utilization of the amount of stretchavailable in the long string of tubing to operate a plunger for pumpingpurposes and the invention contemplates any combination of mechanicalelements by which this principle may be utilized.

The nature and objects of the present invention having been thusdescribed and illustrated what is claimed as new and useful and isdesired to be secured by Letters Patent is:

l. An apparatus for producing oil from a subsurface formation whichcomprises a tubing for carrying said fluid extending from the surfacesubstantially to said formation, an oil collection chamber carried bythe end of said tubing, an entrance for oil from said formation intosaid chamber, a passage for oil from said chamber into said tubing, apiston adapted by reciprocation to force fluid from said chamber intosaid tubing, an elongated rigid fluid conducting hollow rod connectingsaid piston to the surface, and means at the surface for applying fluidpressure to the interior of said hollow rod to thereby extend said rodand actuate said piston.

2. An apparatusfor pumping fluid to the surface from a subsurfaceformation comprising a tubing for carrying said fluid extending from thesurface substantially to said formation, a chamber carried by the lowerend of said tubing, means for admitting fluid from said formation intosaid chamber, means for admitting fluid from said chamber into saidtubing, a cylinder arranged in said chamber, a piston arranged in saidcylinder adapted to exclude formation fluid from the portion of thecylinder above said piston, a fluid-conducting hollow rod connectingsaid piston to the surface, means for admitting fluid from said hollowrod to said cylinder behind said piston, and means for applying fluidpressure to said hollow rod.

3. An apparatus according to claim 2 in which there is provided in saidcylinder an annular surface rigidly related to the tubing and adapted,by affording a working surface for the pressure fluid admitted into saidcylinder behind said piston, to exert an upward thrust against saidtubing when pressure fluid is applied to said piston to thereby preventstretching of said tubing.

4. An apparatus according to claim 2 in which means are provided at thesurface for alternately applying fluid pressure to said piston andreleasing said pressure.

5. An apparatus for producing oil from a subsurface iormation whichcomprises a tubing for carrying said fluid extending from the surfacesubstantially to the formation, an oil collection chamber carried by theend of said tubing, an entrance for oil from said formation to saidchamber, a passage for oil from said chamber into said tubing, 2. pistonadapted by reciprocation to force fluid from said chamber into saidtubing, means adapted to be arranged at the surface for actuatinghydraulic fluid for operm ating said piston, and a pipe for conductingsaid hydraulic fluid from the surface to said piston connected to saidpiston, said pipe being of such length and tensile strength that, uponapplication of suflicient pressure to said piston, it will stretchsufficiently to provide the downward travel of said piston, and upon therelease of said pressure will contract and move the piston upwardly.

IVAN S. SALNIKOV.

